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Can't get arrow volume plot arrows to point in the right direction
Posted 23.12.2015, 08:53 GMT-5 2 Replies
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I'm trying to model flow inside a rotating pipe.
I think I have managed to set up the model correctly, the results in most plots look intuitively correct.
However, when I try the arrow volume plot for the fluid velocity, I get a situation where although the arrows are in the right location and have the right magnitude, they are not pointing in the direction of the local fluid velocity vector. Rather they all end up pointing along the (negative) y-axis.
I assume I am missing a link or checkbox somewhere, but I don't know where.
What am I doing wrong?
I think I have managed to set up the model correctly, the results in most plots look intuitively correct.
However, when I try the arrow volume plot for the fluid velocity, I get a situation where although the arrows are in the right location and have the right magnitude, they are not pointing in the direction of the local fluid velocity vector. Rather they all end up pointing along the (negative) y-axis.
I assume I am missing a link or checkbox somewhere, but I don't know where.
What am I doing wrong?
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2 Replies Last Post 23.12.2015, 11:54 GMT-5
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Posted:
9 years ago
Hi
indeed, not very logical, I assume it's in Z you expected the flow ?
It seems to me that you have made a 2D-axi model and mapped/revolved it to 3D ?
My best guess then, what happens easily, is that the default vector components in the plot field entries are not ordered as you expected them to be. Check carefully the 3 vector components of the Arrow plot and be sure they are in the correct order.
This has happened a few times to me when revolving 2D-axi models. COMSOL is applying 2D-axi logic also onto the 3D plots, which is not the best fit ;)
Merry X-mas :)
--
Good luck
Ivar
indeed, not very logical, I assume it's in Z you expected the flow ?
It seems to me that you have made a 2D-axi model and mapped/revolved it to 3D ?
My best guess then, what happens easily, is that the default vector components in the plot field entries are not ordered as you expected them to be. Check carefully the 3 vector components of the Arrow plot and be sure they are in the correct order.
This has happened a few times to me when revolving 2D-axi models. COMSOL is applying 2D-axi logic also onto the 3D plots, which is not the best fit ;)
Merry X-mas :)
--
Good luck
Ivar
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Posted:
9 years ago
Thanks Ivar, you are right.
That's exactly how I did it.
I'm actually expecting primarily azimuthal (rotational) flow since the pipe is spinning.
Re-ordering u,v and w doesn't seem to do it. I can possibly fudge it with adding some trigonometry to correctly map vector components, but I'm wondering if the 2D-axi model is maybe an oversimplication for this model.
I'll try 3D and see where that gets me.
-G
That's exactly how I did it.
I'm actually expecting primarily azimuthal (rotational) flow since the pipe is spinning.
Re-ordering u,v and w doesn't seem to do it. I can possibly fudge it with adding some trigonometry to correctly map vector components, but I'm wondering if the 2D-axi model is maybe an oversimplication for this model.
I'll try 3D and see where that gets me.
-G